1. Field of the invention
This invention relates to an order wire switchable to a public line, used in a telephone communication system.
2. Description of the Related Arts
An order wire which is an auxiliary circuit for use in the line-up and maintenance of telephone communication facilities has been employed in parallel to telephone trunk connecting between a repeater station and a switching station or another repeater station.
Thus, the order wire is isolated from the telephone system. An Engineer at the repeater station may require to speak to a person outside the station opposite across the order wire. Then, the Engineer must ask, via the order wire a person in the opposite station to convey his message to the outside person, or the Engineer must go out of the repeater station to look for a public telephone. However, the repeater station is often located in a rural area where no public telephone service is accessible available.